CeNS Colloquium

Martin Koch
Department of Physics, Philipps University Marburg

In the last few years spectroscopy at terahertz (THz) frequencies, i.e. in the range between 0.1 and a few THz has enjoyed increasing interest for two reasons. Firstly, a lot of fundamental excitations in matter have transition energies in the meV range. Hence, they can be excited by THz photons. Examples include molecular vibrations, phonons in crystalline solids and intra-excitonic transitions; to name only a few. Secondly, a multitude of applications have been discussed for THz systems, ranging from medical diagnostics and security applications to the monitoring of industrial production processes.

In this talk we first will give examples for basic research applications of THz spectroscopy systems. In particular we investigate intra-excitonic Rabi flopping in semiconductor heterostructures where we find strong indications for a THz-induced reversible and irreversible coherent population transfer.

Furthermore, we will discuss several real-world applications of THz spectroscopy systems and the recent progress in the development of these systems.